1. Field of the Invention
Disclosed is a stone material that has had its natural color enhanced by heating to a specific temperature. More specifically, the subject invention entails selecting a suitable stone material and heating that stone material through at least one and usually two stages of heating to produce a product that has its colors greatly enhanced over the starting shades of the stone material.
2. Description of the Background Art
Heating has been utilized in the process of thoroughly drying and curing glazes used on pottery and tiles for centuries. Depending upon the exact composition of a glaze or its equivalent and the application procedure, various colors and textures can be generated for the pottery and tiles. However, a color enhancement of the underlying material itself (clays, common stone materials, and the like) is not accomplished without the use of a glaze or similar added substance.
It is also noted that the heating of highly colored and hydrated chemicals (like copper (II) sulfate pentahydrate and many others) produces products that are much less intensely colored (bright blue to bluish-white for the change in heated copper (II) sulfate pentahydrate). Heat dehydrated or even oxidized inorganics simply are less intensely colored than the original hydrated starting materials.
Specifically, U.S. Pat. No. 5,084,909 describes color enhancement brought about in natural and synthetic gem materials by high energy gamma ray fields for extended periods of time (50 to 1000 hours). High energy radiation fields are necessary for this process. It is extremely interesting to note that disclosed in this reference the inventor utilized heat to bleach or remove unwanted colors from the gems (either before or after a well known color enhancement procedure that involved electron bombardment). Therefore, this reference clearly teaches that heat has been utilized not to enhance color but to lessen color intensity in at least gem-type materials.
U.S. Pat. No. 5,477,055 presents a thorough review of the history of coloring precious or semi-precious gem stones via single or combined radiation treatments. The color enhancement process related is a two step method that includes fast neutron irradiation at between 350.degree. C. to 600.degree. C. followed by gamma ray or electron bombardment. Higher temperatures tend to fragment the gem stones. The elevated temperatures (above room temperature) tend to reduce unwanted side (blue-gray) colors.
Presented in U.S. Pat. No. 4,749,869 is a process for irradiating topaz and the product resulting therefrom. A three step method of color enhancement is described in which a sample stone is: 1) exposed to high energy neutrons; 2) exposed to electrons; and 3) heated to between 250.degree. F. (121.degree. C.) and 900.degree. F. (482.degree. C.). The heating step tends to "bleach-out" or remove unwanted side colors, thereby enhancing the desired blue color.
Diamonds may be heat treated to increase desirable colorations. U.S. Pat. No. 2,945,793 illustrates this approach to coloring diamonds. Irradiation by electrons in followed by heating to about 500.degree. C. to, once again, decrease undesirable tints within the diamond.
U.S. Pat. No. 5,568,391 shows an automated tile mosaic creation system in which one step involves heating a glazed tile. The firing of the tiles is merely to cure the glaze into the desired final shade and hardness.
The foregoing patents reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully submitted, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant's claimed invention.